The present invention generally relates to gaming apparatus and, more particularly, to electronic reel-type slot machines having a plurality of reels rotatable about a common axis. In a typical reel-type slot machine, a payoff is made to a player when a winning set of symbols is displayed on the pay line(s) of the machine. To start play, a button is pushed or a handle is pulled to initiate rotation of the reels.
In one type of design, the angular positions of the reels, after they have been stopped, is detected and the appropriate payoff amount, if any, is calculated and paid to the player. Another approach in modern machines uses random number generation to select the symbols to be displayed on the pay line(s). The payoff is determined based on a pay table which contains payoff amounts for the various symbol combinations.
In order to stimulate player interest in such machines, it is desirable to add additional features and novelties to provide entertainment by incorporating different strategies and features which attract player interest. Through the use of a microprocessor based controller system including a stepper motor for positioning the reels it is possible to provide simulations and features that are somewhat unusual and interesting to the players.
According to the present invention and in addition to the usual spin and payoff cycle of a slot machine, there is provided a wildcard symbol on one of the reels. Its appearance on the pay line is used to trigger a supplemental pay off under certain circumstances. During the supplemental pay off sequence, the reel on which the wild symbol appears is caused to shake or jitter while coins fall into the trough as if money were being shaken off a tree.